The intense commercialization of metallocene polyolefin catalysts (metallocene being cyclopentadienyl based transition metal catalyst compounds) has led to widespread interest in the design of non-metallocene, homogeneous catalysts, particularly for use in the economical gas and slurry phase processes. This field is more than an academic curiosity as new, non-metallocene catalysts in gas or slurry phase may provide an easier, more economical pathway to currently available products and may also provide product and process opportunities which are beyond the capability of metallocene catalysts in the gas or slurry phase.
Anionic, multidentate heteroatom ligands have received the most attention in non-metallocene polyolefins catalysis. Notable classes of bidentate anionic ligands which form active polymerization catalysts include N—N and N ligand sets. Examples of these types of non-metallocene catalysts include amidopyridines (Kempe, R., “Aminopyridinato Ligands —New Directions and Limitations”, 80th Canadian Society for Chemistry Meeting, Windsor, Ontario, Canada, Jun. 1-4, 1997. Kempe, R. et al, Inorg. Chem. 1996 vol 35 6742.) Likewise, recent reports by Jordan et al. of polyolefin catalysts based on hydroxyquinolines (Bei, X.; Swenson, D. C.; Jordan, R. F., Organometallics 1997, 16, 3282) have been interesting even though the catalytic activities of Jordan's hydroxyquinoline catalysts are low.
Schrock et al in U.S. Pat. No. 5,889,128 discloses a process for the living polymerization of olefins in solution using initiators having a metal atom and a ligand having two group 15 atoms and a group 16 atom or three group 15 atoms. In particular, the solution phase polymerization of ethylene using {[NON]ZrMe} [MeB(C6F5)31 or {[NON]ZrMe(PhNMe2)]}[B(C6F5)41 is disclosed in examples 9 and 10.
EP 893 454 A1 discloses unsupported transition metal amide compounds used in combination with activators to polymerize olefins in the solution phase.
Ethylenebis(salicylideneiminato)zirconium dichloride combined with methyl alumoxane deposited on a support and unsupported versions were used to polymerize ethylene by Repo et al in Macromolecules 1997, 30, 171-175.
Thus there is a need in the art for gas or slurry phase processes to produce polyolefins using new and different supported catalyst systems.